A self-confessed paedophile who sexually abused several boys in Sydney is being harboured by a leading Los Angeles Jewish welfare group.

The man, who is being investigated by NSW detectives over several sexual assaults at Bondi's Yeshiva school in the 1980s, has been shielded from exposure and scrutiny by Jewish Family Service of Los Angeles.

The service, more than 150 years old, provides medical, housing, food, counselling, educational and family support services.

Emails obtained from US sources show that since mid-2011 its board members have been aware of the man's sexual abuse history in Australia but have not reported him to authorities in Sydney or the US.

In an email to the man in November 2011, Debbie Fox, executive director of the Los Angeles organisation, refers to phone calls to board members about his activities in Sydney.

''I have no idea how anyone found out - but calls are coming daily from many sources. So far, we've been protecting you.''

The revelation that a big Jewish organisation in the US is protecting a known paedophile comes at a time when orthodox communities around the world are being challenged about their historical preference for handling of child sex abuse cases internally rather than involving the police.

The man is central to the controversy surrounding Bondi's Yeshiva community and some of Australia's most senior rabbis.

Emails show the Jewish Family Service conducted an ''evaluation'' of the man, who is not being named for legal reasons, to see if he was still a risk to children.

The evaluation included assessments by doctors and psychologists, and the man undertaking a lie detector test.

In her email, Ms Fox expressed frustration at how long the man was taking to complete the process, writing ''we have NEVER had any evaluation take nearly this long.

''For your security - you must complete it and we must get the evaluation report and recommendations,'' she wrote.

It is believed the man did not pass the evaluation and remains under strict controls to prevent his being with children unsupervised. Ms Fox did not respond to questions.

The emails show the man's history as a sexual abuser has not been made known to most members of the Jewish community he mixes with in LA. Close members of his family in Australia and the US are also understood to be unaware of his past.

It was revealed this year during a recent conversation with one of his victims that the man admitted to regular and serious sexual abuse of several boys in the 1980s.

NSW police are understood to have a recording of this conversation. In it, the man says Yeshiva's spiritual leader Rabbi Pinchus Feldman confronted him about a sexual abuse incident in the mid-1980s.

In February, Rabbi Feldman released a statement saying he had no recollection of anyone confessing to child sexual abuse 25 years ago and that he encouraged anyone with knowledge of such crimes to go to the police.

The man who admitted to sexually abusing boys at Yeshiva left Sydney to find a wife in Los Angeles. But after a few weeks he returned to Sydney and continued sexually abusing boys. He eventually settled in Los Angeles.

The head of the Organisation of Rabbis of Australasia, Moshe Gutnick, said last month that he had received an anonymous phone call about 25 years ago from a boy who claimed to have been sexually abused by the man.

Rabbi Gutnick said, with hindsight, he should have alerted police. But he had told senior leaders of the Yeshiva community.